1. Field of the Invention
This invention relates to marine transport systems and to procedures and structures in furtherance thereof. More particularly, the invention relates to a marine transport system in which modularization of cargo holds, docks, and transport vessels is maximized, the cargo holds preferably defining the entire cargo carrying capacity of a given vessel in the system and being interchangeable between vessels.
2. The State of the Art
At the present time, transport of cargo by water is, as a general rule, the most economical mode of transport available. In many instances, however, the cost differentials between sea and land transport, or between sea and air transport, in combination with the time differentials similarly involved, render land or air transport preferable to sea transport. If the cost of sea transport can be substantially reduced, the use of sea transport in preference to land or air transport would be increased to the advantage of the substantial maritime investment in the nation, as well as to the long term military advantage of the country.
The most significant single factor contributing to the total cost of transport of goods and materials by sea lies in cargo-handling expense. In break-bulk shipment of cargo by sea, wherein individual containers or small combinations or pallets of individual boxes, bags or other containers are loaded separately onto the transport vessel, manual handling of cargo occurs at many different points in the shipping process. In break-bulk shipment procedures, cargo is manually assembled and classified at a warehouse such as a manufacturers' warehouse or cartage broker's warehouse. Next the cargo is transferred to surface transport vehicles, another cargo handling operation, for transport to a transit shed located in the dock area. Upon arrival of the vehicle at the transit shed, the cargo is again handled as it is transferred from the vehicle to storage locations in the transit shed. Subsequently, the cargo is transferred from the transit shed to dockside; in this process, the cargo is handled both upon removal from the transit shed and upon deposit at dockside. Still later, the cargo is removed from dockside to the cargo hold of the ship by the use of the cargo handling gear located either at dockside or upon the vessel; this procedure involves two additional cargo handling operations. Upon deposit of the cargo within the vessel, it is frequently moved within the vessel by stevedores since the cargo handling gear of a conventional shelterdeck vessel, for example, does not provide access to all cargo stowage locations of the vessel. Upon arrival of the vessel at its destination, a reverse cargo handling procedure is involved. Therefore, it is seen that approximately sixteen separate cargo handling procedures are involved in the marine transport of cargo from original source to ultimate destination. Each cargo handling operation involves manual labor performed with or without the assistance of mechanized cargo handling devices. It is well known that labor cost, rather than equipment cost, is the single most expensive item in any process performed practically anywhere in the world at the present time, particularly so in the United States.
In view of the above-described uneconomical characteristics of break-bulk cargo handling procedures, and in an effort to reduce the overall cost of marine transport, advances in the containerization of cargo have been realized in the United States as well as abroad. By these advances, the cargo handling process from manufacturer's warehouse to ship and from ship to destination warehouse has been simplified by the elimination of the transit shed. In this process, cargo is transferred directly from the manufacturer's warehouse, e.g., to dockside in a container which conventionally is the cargo van of a tractor-drawn cargo trailer (semi-truck trailer), the van being removable from its supporting wheels in the most advanced containerization operations presently in commercial use. These truck vans ultimately are loaded directly aboard the vessel, but in the interim between dispatch from the manufacturer's warehouse and loading aboard ship or barge, the vans must be assembled in a staging area adjacent to dockside from which they are later moved to the vessel. According to current containerization practices, cargo handling procedures involving manual labor occur fourteen times, as opposed to sixteen times with break-bulk cargos, in transport of a given item of cargo from manufacturer's warehouse or the like to destination warehouse. The basic practical advantage over break-bulk cargo handling techniques of containerization systems of the type described above is the reduction in the extent to which individual cargo packages are handled. That is, greater quantities of cargo are dealt with in each cargo handling operation with the result that handling costs per individual commercial unit of cargo are reduced to a greater extent than the reduction in the total number of cargo handling operations involved.